Asbestosis

Abstract

Pulmonary Asbestosis differs from the other pneumoconioses under discussion by reason of the nature of the particles inhaled, and by reason of their different chemical composition. Further, the shape of the particles causes them to be arrested more often in the bronchioles than in the alveoli, and their size and shape render them incapable of being readily transported into the lymphatic system. One is, therefore, not surprised to find that Pulmonary Asbestosis gives quite a different pathological, and therefore radiological, appearance to most other forms of pneumoconiosis. Asbestos is composed of long, silky fibres, like fine strands of glass, held together by a fine fibrous network. In the manufacturing process these fibres are broken up into short lengths, and in some cases they are ground down into fine dust. The asbestos content of the air varies considerably in the different processes utilised, but is highest in the textile branch of the industry. When examined microscopically by dark ground illumination, the fibre gives the impression of a sharp, brittle, metallic wire, broken off at different angles and in different lengths; and, being highly refractile, it has the appearance of the glowing filament of an electric bulb. Chemically it is a silicate of iron and magnesium, and does not contain a free silica. The shape of the asbestos particles inhaled causes them to be arrested in the terminal bronchioles, and a deposit of iron-containing material forms over them.